/* 官网样式：苹果的做法——大量留白、一种强调色、靠灰度和大小分层，不用渐变、彩色图标和重投影。 */
:root {
  --bg: #fff;
  --tile: #f5f5f7;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --line: #d2d2d7;
  --blue: #0066cc;
  --button: #0071e3;
  --mark: rgba(0, 113, 227, .16);
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000;
    --tile: #161617;
    --text: #f5f5f7;
    --muted: #a1a1a6;
    --line: #424245;
    --blue: #2997ff;
    --mark: rgba(41, 151, 255, .28);
  }
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 48px; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.47 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", "PingFang SC", "Segoe UI", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
}
/* 日韩页用各自的字形：放在 PingFang 后面的话，日文汉字会显示成中文字形 */
html[lang="ja"] body { font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", "Hiragino Sans", "Segoe UI", "Yu Gothic UI", Meiryo, sans-serif; line-break: strict; }
html[lang="ko"] body { font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", "Apple SD Gothic Neo", "Segoe UI", "Malgun Gothic", sans-serif; word-break: keep-all; }
/* 日语标题只在 <wbr> 处换行，不把词拆开 */
html[lang="ja"] :is(h1, h2, h3) { word-break: keep-all; }
html[lang="ja"] .split h2 { font-size: clamp(28px, 4vw, 40px); }
img { display: block; max-width: 100%; height: auto; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, p { margin: 0; }
.wrap { max-width: 980px; margin: 0 auto; padding: 0 22px; }

/* 顶栏 */
.nav {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 50%, transparent);
}
.nav .wrap { display: flex; align-items: center; gap: 24px; height: 48px; font-size: 12px; }
.nav a { color: var(--text); opacity: .8; }
.nav a:hover { opacity: 1; text-decoration: none; }
.brand { display: flex; align-items: center; gap: 8px; font-size: 14px; font-weight: 600; opacity: 1 !important; margin-right: auto; }
.brand img { width: 22px; height: 22px; }
.lang { position: relative; }
.lang summary { cursor: pointer; list-style: none; opacity: .8; }
.lang summary::-webkit-details-marker { display: none; }
.lang summary:hover { opacity: 1; }
.lang summary::after { content: " ⌄"; }
.lang div { position: absolute; top: 28px; right: -10px; display: grid; min-width: 112px; padding: 6px; border-radius: 12px; background: var(--bg); border: 1px solid color-mix(in srgb, var(--line) 60%, transparent); }
.lang a { padding: 5px 10px; border-radius: 7px; opacity: 1; white-space: nowrap; }
.lang a:hover { background: var(--tile); }
.lang a[aria-current] { font-weight: 600; }
.nav .get { color: #fff; background: var(--button); opacity: 1; padding: 3px 11px; border-radius: 980px; }

/* 按钮和「了解更多 ›」链接 */
.btn { display: inline-block; padding: 11px 22px; border-radius: 980px; background: var(--button); color: #fff; }
.btn:hover { background: #0077ed; text-decoration: none; }
.more::after { content: " ›"; }
.actions { display: flex; flex-wrap: wrap; justify-content: center; align-items: center; gap: 12px 28px; margin-top: 24px; }

/* 首屏 */
.hero { padding: 88px 0 72px; text-align: center; }
.hero h1 { font-size: clamp(44px, 8vw, 80px); line-height: 1.05; font-weight: 600; letter-spacing: -.015em; }
.hero .lead { max-width: 660px; margin: 16px auto 0; font-size: clamp(19px, 2.6vw, 24px); line-height: 1.35; color: var(--muted); }
.fine { margin-top: 14px; font-size: 12px; color: var(--muted); }

/* 演示：窗口里一段文字，指针停在词上，浮窗挂在词的正下方（和 App 里一样），整个放在窗口之内 */
.demo { max-width: 860px; margin: 64px auto 0; text-align: left; }
.window { background: var(--tile); border-radius: 12px; overflow: hidden; }
.window .bar { display: flex; gap: 7px; align-items: center; height: 36px; padding: 0 14px; }
.window .bar i { width: 11px; height: 11px; border-radius: 50%; background: var(--line); }
.term { max-width: 620px; margin: 0 auto; padding: 20px 28px 356px; font: 14px/1.75 ui-monospace, "SF Mono", Menlo, Consolas, monospace; color: var(--muted); }
.term b { position: relative; font-weight: 400; color: var(--text); background: var(--mark); border-radius: 3px; padding: 1px 2px; }
.term picture { position: absolute; left: 50%; top: calc(100% + 14px); width: 454px; transform: translateX(-50%); }
.cursor { position: absolute; left: 62%; top: 58%; width: 18px; height: 22px; pointer-events: none; }

/* 分区 */
section { padding: 96px 0; }
section.soft { background: var(--tile); }
.head { max-width: 720px; margin: 0 auto 56px; text-align: center; }
.head h2 { font-size: clamp(32px, 5vw, 48px); line-height: 1.1; font-weight: 600; letter-spacing: -.01em; }
.head p { margin-top: 14px; font-size: clamp(17px, 2vw, 21px); line-height: 1.4; color: var(--muted); }
kbd { font: inherit; font-weight: 500; color: var(--text); white-space: nowrap; }

/* 功能：灰底格子，图标只用一种颜色 */
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.cell { padding: 28px; border-radius: 18px; background: var(--tile); }
.cell svg { display: block; width: 28px; height: 28px; margin-bottom: 18px; fill: none; stroke: var(--text); stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; }
.cell h3 { font-size: 19px; font-weight: 600; }
.cell p { margin-top: 6px; font-size: 15px; line-height: 1.45; color: var(--muted); }

/* 两块并排：上面文字，下面截图 */
.pair { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.pair .tile { display: flex; flex-direction: column; padding: 40px 32px 32px; border-radius: 18px; background: var(--tile); text-align: center; }
.tile h3 { font-size: 28px; line-height: 1.15; font-weight: 600; letter-spacing: -.005em; }
.tile p { margin: 10px 0 28px; font-size: 17px; color: var(--muted); }
.tile picture { margin-top: auto; }
.tile img { margin: 0 auto; }

/* 生词本：一张大图，下面三列小字 */
.shot { max-width: 860px; margin: 0 auto; }
.shot img { border-radius: 12px; border: 1px solid color-mix(in srgb, var(--line) 50%, transparent); }
.points { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; margin-top: 48px; }
.points b { display: block; font-weight: 600; }
.points span { font-size: 15px; color: var(--muted); }

/* 隐私：左边文字，右边截图 */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center; }
.split h2 { font-size: clamp(32px, 5vw, 48px); line-height: 1.1; font-weight: 600; letter-spacing: -.01em; }
.split > div > p { margin-top: 14px; font-size: 19px; line-height: 1.4; color: var(--muted); }
.lines { margin: 28px 0 0; padding: 0; list-style: none; font-size: 15px; }
.lines li { padding: 12px 0; border-top: 1px solid color-mix(in srgb, var(--line) 60%, transparent); }
.split img { border-radius: 12px; border: 1px solid color-mix(in srgb, var(--line) 50%, transparent); }

/* 模型：三列，细线分隔 */
.cols { display: grid; grid-template-columns: repeat(3, 1fr); }
.cols > * { padding: 0 28px; border-left: 1px solid color-mix(in srgb, var(--line) 60%, transparent); }
.cols > :first-child { padding-left: 0; border-left: 0; }
.cols > :last-child { padding-right: 0; }
.cols h3 { font-size: 19px; font-weight: 600; }
.cols small { display: block; margin-top: 2px; font-size: 13px; color: var(--muted); }
.cols p { margin-top: 12px; font-size: 15px; color: var(--muted); }

/* 下载 */
.download { text-align: center; }
.download .cols > * { display: block; padding-top: 4px; padding-bottom: 4px; color: var(--text); }
.download .cols > :first-child { padding-left: 28px; }
.download .cols > :last-child { padding-right: 28px; }
.download .cols a:hover { text-decoration: none; }
.download .cols svg { display: block; width: 36px; height: 36px; margin: 0 auto 14px; fill: currentColor; }
.download .cols span { display: block; margin-top: 4px; font-size: 13px; color: var(--muted); }
.download .cols em { display: block; margin-top: 12px; font-style: normal; font-size: 15px; color: var(--blue); }
.download .cols em::after { content: " ↓"; }
.download .cols a:hover em { text-decoration: underline; }
.notes { max-width: 720px; margin: 56px auto 0; font-size: 12px; line-height: 1.5; color: var(--muted); text-align: left; }
.notes p + p { margin-top: 8px; }
.changes { max-width: 720px; margin: 28px auto 0; text-align: left; font-size: 14px; }
.changes summary { cursor: pointer; color: var(--blue); }
.changes ul { margin: 14px 0 0; padding-left: 18px; color: var(--muted); }
.changes li + li { margin-top: 8px; }

footer { padding: 20px 0 36px; background: var(--tile); font-size: 12px; color: var(--muted); }
footer .wrap { display: flex; flex-wrap: wrap; gap: 8px 24px; }
footer nav { display: flex; gap: 16px; margin-left: auto; }
footer a { color: var(--muted); }

@media (max-width: 760px) {
  section { padding: 64px 0; }
  .hero { padding-top: 56px; }
  .nav .hide { display: none; }
  .grid, .pair, .split, .points, .cols { grid-template-columns: 1fr; }
  .cols > *, .cols > :first-child, .cols > :last-child { padding: 20px 0; border-left: 0; border-top: 1px solid color-mix(in srgb, var(--line) 60%, transparent); }
  .cols > :first-child { border-top: 0; }
  /* 窄屏放不下 454 宽的浮窗：缩到屏幕宽，贴着左右边，词换到哪一行都接在文字下面 */
  .term { padding: 16px 20px 20px; font-size: 13px; max-width: none; }
  .term b { position: static; }
  .term picture { display: none; }
  .cursor { display: none; }
}

.demo > picture { display: none; }
@media (max-width: 760px) { .demo > picture { display: block; margin-top: 12px; } }

/* 标题不留孤字 */
h1, h2, h3, .lead, .head p { text-wrap: balance; }